Serum beta 2-microglobulin: a real improvement in the management of multiple myeloma?

Beta 2-microglobulin (B2-m) determinations in serum have recently been introduced as a method of stratifying patients suffering from multiple myeloma. Conflicting results from several studies prompted us to study retrospectively the correlation of B2-m with presenting features and disease stage, as well as the prognostic value of B2-m, in 87 myeloma patients. Significant correlations were found between B2-m and presenting features such as haemoglobin level, serum calcium level and total body myeloma cell mass. The strongest correlation existed between B2-m and serum creatinine (r = 0.68). B2-m did not discriminate between the different disease stages as defined by Durie and Salmon, nor between myeloma Stage IA and monoclonal gammopathy of undetermined significance (MGUS). Considered alone, B2-m was found to have prognostic value in terms of survival. This correlation disappeared after correction for serum creatinine level and tumour load (multivariate analysis). Furthermore, changes in tumour load during therapy were not reflected in changes in B2-m levels, thereby rendering B2-m levels invalid as tumour marker. Our findings indicate no value for B2-m determinations in the staging and follow-up of myeloma patients.